The lignocellulosic complex represents the most abundant biopolymer on Earth and constitutes the main component of a great variety of wastes and residues from domestic and industrial activities of man. Moreover, it is present in profuse biological materials, such as wood, grass, straw, and forage. Due to its immediate origin in a biological process, this biopolymer complex has received the name of lignocellulosic biomass. Being the most plentiful material in the biosphere, the use of the lignocellulosic biomass will allow the production of a valuable biofuel like bioethanol as well as the economic exploitation of a wide range of potential feedstocks resulting from domestic, agricultural, and industrial activities.